tonight in mountain view nasa shows off technology that will pay big dividends during fire season. its coming up in a half hour at 6:00. now back to dan and cheryl. >> students at san francisco city college shared ideas on making the campus greener. >> that is right this, car aimed at reducing the number of cars on the road. >> they feel like selling produce is going to help armers -- farmers and provide healthier food for students. >> yes. they want the college to become more sustainable by expanding programs. >> all goodas. that is going to do it for us. >> i'm sirldnings. for watching. we'll se >>> this is "world news." tonight, two fast-moving stories. in boston, the breaking news. the fbi says they want everybody to help find these two men on the surveillance tape. persons of interest in the boston marathon bombing. we'll take you frame by frame through the video. why the fbi says, look at every detail. and the breakthrough comes as an emotional president tonight has a message for the bombers. >> we will find you. and, yes, you will face justice. >>> also tonight, that texas d